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Not applicable.
The present invention generally relates to product identification and more particularly to the ability to mark cold glass, such as cold glass picture tube components.
Marking of cold glass becomes even more challenging when subsequent downstream processing involves high temperature, e.g., Lehr processing of glass picture tubes. Another example is flat glass where individual pieces require bar code identification when they are cut from a larger parent piece. These pieces may be later tempered. If they are tempered, the markings must survive high annealing temperatures, e.g., about 600xc2x0 C. A further example is individual piece identification of catalytic converter ceramic cores, which may need to survive high temperature (e.g., 600xc2x0 C.) temperatures during downstream coating and curing processing.
Glass part manufacturers and processors require individual piece marking, which may be produced and/or applied on-site and, when used, provides high contrast (e.g., black/white) man readable and/or machine readable (e.g., bar code) indicia that can be read using standard readers (e.g., bar code readers).
U.S. Pat. No. 6,479,208 discloses labels that are produced onto hot (e.g., just out of the mold) glass components by a tape transfer technique. The present invention is addressed to the marking of a wide variety of relatively cooler (from ambient temperature to about 800xc2x0 F.) glass pieces, which may or may not experience high temperature downstream processing.
A method for marking cold (e.g., about room temperature to 800xc2x0 F.) substrates (e.g., glass, ceramics, metals) commences by creating a tape of a carrier backing bearing a laser ablatable, non-tacky coating with optional barrier and release coatings between the carrier backing and the coating. The coating is laser ablated to form one or more of alphanumeric characters or graphics on the carrier backing. The ablated coating on the carrier backing is heated to form a tacky film of the coating on the carrier backing. The tacky film is roller transferred from the carrier backing onto a pliable transfer pad. Finally, the tacky film is roller transferred from the pliable transfer pad onto the cold substrate for its marking.